SUBORDER JUGATAE 75 



open in any way without injuring the larva within. The 

 coccon, in the case of E. auricyanea is about 2 mm. by 4 mm. 

 and is made of whitish silk with small grains of earth and 

 sand firmly incorporated in its surface. 



All this is finished by about the middle of May. In this 

 cocoon it then stays until the following April, a period of 

 eleven months or more. This disproportion of the resting 

 to the active period is the more remarkable in that for eight 

 or nine of the eleven months it is in the larval condition 

 apparently unchanged, the pupal period being relatively 

 short. 



It is not illogical, however, for meanwhile there are no 

 enfolded, and very young uncutinized leaves for the insertion 

 of eggs; nor young, soft growing leaves to be food for the 

 larvae. When these conditions come again another genera- 

 tion is begun and not before. 



Perhaps there is a connection between the long larval 

 rest and the remarkable form of the pupa that is at length 

 to be found in the cocoons. For whereas the head of the 

 larva is small with mouth parts in proportion; and whereas 

 the mandibles, in particular, of the adult are small, weak, 

 and non functional, the mandibles of the pupa are — in pro- 

 portion to the rest of it — immense structures; and they are 

 functional, being used to tear open the strong cocoon and 

 to dig a way out of the soil when the pupa is mature and 

 ready for the emergence of the adult. 



Pupae.- — The pupa, like the larva, very nearly fills the 

 cocoon. It has all appendages free and unfused and all the 

 segments of the body are movable. The head especially 

 can be moved up and down and sidewise. There is no room 

 in the cocoon for these movements, but if a pupa be taken 

 out and lightly touched with a brush, it responds, according 

 to Busck and Boving, with a grotesque nodding of its head 

 and with the swinging out of the enormous mandibles in a 

 deliberate manner. Movement is particularly free in the 



